DE69002047T2 - Pipe coupling. - Google Patents

Description

The invention relates to a coupling for connecting pipes.

A known pipe coupling, as shown for example in Fig. 8, has a sleeve 5 with an inclined inner surface 50, which is arranged in a large-diameter end section 11 of a through-bore of a coupling body 1. The surface 50 is inclined such that the diameter decreases in the axial direction towards an opening.

In addition, an insert 3, which has a through hole that leads to a small diameter bore section of the coupling body 1, is slidably mounted in this coupling body 1 together with a clamping sleeve 4. The latter has an outer peripheral surface 40 that comes into contact with the inclined inner surface 50 of the sleeve 5 and is designed in such a way that it can increase or decrease its diameter when axially displaced within the sleeve 5.

It is only possible to attach the three parts, namely the sleeve 5, the insert 3 and the clamping sleeve 4, of the known pipe coupling if the large diameter section 11 of the coupling part 1 is relatively wide. Therefore, when manufacturing the coupling body 1, the wall thickness around the large diameter bore section must be reduced significantly. This results in problems with dimensional accuracy when manufacturing the larger diameter bore section 11 of the coupling body 1.

A well-known pipe coupling of the type described also makes Cost problems, since the manufacture of the sleeve 5 requires machining on a lathe or the like in order to obtain the inclined inner peripheral surface 50.

Another problem with the well-known pipe coupling is that it cannot be reused. Once a hose or pipe H is connected to the pipe coupling, they can no longer be separated from each other.

The known pipe coupling is constructed according to Fig. 8 in such a way that the insert 3 is arranged coaxially and slidably within the cylindrical coupling body 1, which has an external thread at one end, and that the clamping sleeve 4 is inserted between the insert 3 and the coupling body 1 in such a way that the clamping sleeve 4 can move freely forwards or backwards therein. Thus assembled, it can hold a pipe or a hose H, which is inserted between the insert 3 and the clamping sleeve 4, in an inseparable manner by means of the holding forces of these parts.

For this purpose, the coupling body 1 has a pipe insertion opening 11a at one end, as shown in Fig. 8, and the conical sleeve 5 with its inner diameter decreasing in the direction of this insertion opening 11 is arranged behind this opening.

The clamping sleeve 4 is made of resilient material and has an outer diameter slightly larger than the diameter of the pipe insertion opening 11a so that it is frictionally fitted therein. It also has a slot 42 in its peripheral wall which is open towards the pipe insertion opening 11a.

The gap between the clamping sleeve 4 and the insert 3 is slightly smaller than the thickness of the pipe or hose H to be connected to the coupling body 1. So if a pipe is pushed through the pipe insertion opening 11a with force and between the clamping sleeve 4 and the insert 3, and then the pipe is pulled, the clamping sleeve 4 and the insert 3 together with the pipe are caused to move in the direction of the pipe insertion opening 11a. As soon as the clamping sleeve 4 hits the inclined surface 50, the conical sleeve 5 exerts a pressing force on the clamping sleeve 4 in the direction of a diameter reduction, so that the holding force exerted by the clamping sleeve 4 and the insert 3 on the pipe is increased and the pipe is held in an indetachable manner.

This pipe coupling is very practical in that a pipe can be connected to it very easily by simply inserting it through the pipe insertion opening 11a and then pulling it back.

However, with the type of pipe coupling described above, there is a risk that if the collet 4 wears out after a long period of use, the collet may break when a retained pipe is pushed inward. If this occurs, a firm connection force can no longer be maintained when the pipe is retracted.

Based on this situation, it is an object of the present invention to create a pipe coupling which can be manufactured relatively easily and at low cost.

A further object of the invention is to provide a pipe coupling from which a pipe or hose can be detached again after it has been connected to it, so that this pipe coupling can be reused.

A further object of the invention is to provide a pipe connection which not only solves the problems mentioned above but also creates a connection of a pipe in a stable state in which the pipe is prevented from moving instead of exerting a compressive force on the pipe.

A pipe coupling comprising a cylindrical body open at both ends and formed from two parts, namely a first part forming a connecting portion at one end of the body and a second part having the shape of a plug element at its end remote from the connecting portion of the first part and forming a pipe insertion opening at the other end of the body, the second part further comprising a conical inner surface tapering in diameter toward the pipe insertion opening; and comprising a cylindrical insert slidably supported within the body and a clamping sleeve disposed between the tapered diameter inner surface and the insert so as to be freely slidable back and forth, leaving a gap between the clamping sleeve and the insert for receiving and retaining the end edge of a tube inserted into the opening, is known from the prior publication FR-A-2398958 (corresponding to GB-A-1603670).

With this design of a pipe coupling, it is no longer necessary to reduce the strength of the coupling body, since the plug element is formed as a separate part which is connected to the first part of the pipe coupling body, and the plug element can be manufactured by drawing a pipe section.

The pipe coupling according to the present invention differs from that known from the above-mentioned prior art in that the insert is displaceable over a predetermined range in the first part, which has an inwardly directed projection on its end opposite the insertion opening to prevent the insert from escaping from this opening.

Advantageously, the first part of the coupling body is in the form of a nipple having a through-bore with a small diameter and a large diameter section and a circumferential groove on its outside to which the plug element is fastened. The insert is slidably held in the large diameter section of the through-bore with the interposition of a sealing element, and the insert in turn has a through-bore which is aligned with the smaller diameter bore section of the nipple.

In this structure, the thickness of the nipple does not need to be reduced in the area of the large diameter portion of the through hole, since the plug element is attached as a separate part to the large diameter side of the nipple and the clamping sleeve is arranged inside the plug element.

The plug element is advantageously removable from the first part of the coupling body, whether in the form of a nipple or otherwise designed, so that genuine reuse is possible.

In further advantageous embodiments of the pipe coupling according to the invention, a C-shaped snap ring is arranged in a groove of the outer surface of the insert, the outer diameter of the snap ring in the non-compressed state being larger than the diameter of the large diameter bore section of the nipple, whereby the insert is prevented from sliding back into the nipple once it has been moved sufficiently far in the direction of the pipe insertion opening to remove the snap ring from the To release the hole.

Particular embodiments of the invention are described below in conjunction with the accompanying drawings, in which show:

Fig. 1a and 1b show a first embodiment of the pipe coupling according to the invention, partly in longitudinal section, Fig. 1a showing the pipe coupling before connection to a pipe and Fig. 1b showing the position assumed by the parts when an internal pressure is exerted on the connected pipe;

Fig. 2a, 2b and 2c show a second embodiment of the pipe coupling according to the invention, also partially in longitudinal section, Fig. 2a showing a pipe connected to the pipe coupling, Fig. 2b showing the process of releasing the pipe coupling from the pipe and Fig. 2c showing the pipe coupling and the pipe after separation;

Fig. 3 shows a partial longitudinal section through a third embodiment of the pipe coupling according to the invention;

Fig. 4a, 4b and 4c are enlarged partial sectional views showing the relationship between the large diameter bore portion of the nipple and the C-shaped snap ring of the embodiment of Fig. 3;

Fig. 5 is a top view of the C-shaped snap ring;

Fig. 6 shows a partial longitudinal section through a clamping sleeve used in the embodiment according to Fig. 3;

Fig. 7 is a view similar to Fig. 3, showing the position of the parts when a pipe is connected to the third embodiment of the pipe coupling; and

Fig. 8 shows a previously described known pipe coupling, partly in longitudinal section.

As shown in Figs. 1 and 2 of the drawing, a pipe coupling designed according to the invention has a main body in the form of a nipple 1, a plug element 2, an insert 3 and a clamping sleeve 4.

The nipple 1 has a through bore with a small diameter portion 10 and a large diameter portion 11. On its outside it has a circumferential groove 12 at one end, namely at the end with the large diameter bore portion 11, and it has an external thread 13 forming a connecting portion at the other end, that is in the region of the small diameter bore portion. The nipple 1 also has an inwardly directed annular projection 15 at its end with the large diameter bore portion 11 remote from the small diameter bore portion 10 to prevent leakage of the insert 3, as will be described.

The plug element 2 is fastened in the circumferential groove 12 of the nipple 1 and has an inclined wall which forms an inner side 21 inclined in such a way that the inner diameter of the plug element decreases in the direction of an opening 20 at the free end of the plug element 2. The plug element 2 can be fixed inseparably in the circumferential groove 12 of the nipple 1 by caulking, as is the case in the embodiment according to Fig. 1.

In the embodiment shown in Fig. 2, when connecting the plug element 2 to the nipple 1 (see Fig. 2a), a ball 23, the diameter of which is larger than the thickness of the plug element 2, is inserted into an opening 22 formed near the end of the plug element 2 to be connected to the nipple 1, and by arranging an outer sleeve 24, the ball is pressed into the circumferential groove 12 of the nipple 1. The outer sleeve 24, in turn, is pressed resiliently against the nipple 1 by means of a spring 27, which is clamped between an inwardly projecting part 25 of the outer sleeve 24 and an outer ring web 26 of the plug element 2. In order to release the plug element 2 from the nipple 1 (see Fig. 2b), the outer sleeve 24 is pulled back against the force of the spring 27 in the direction of the plug element 2, so that the ball 23 can pass from the circumferential groove 12 of the nipple 1 into a recess 28 in the inner surface of the outer sleeve 24. In this embodiment, the plug element 2 and the nipple 1 can be separated again later, wherever necessary.

The manufacture of the plug element 2 from a metallic pipe section or other pipe material of the same thickness reduces the overall manufacturing costs for the pipe coupling in comparison to previously known pipe couplings of a comparable type. The drawing of the pipe material to form the inclined inner surface 21 does not require laborious processing, as was necessary in the known type (Fig. 8) to form the conical insert 5.

One end of the insert 3 is slidably disposed in the large-diameter bore portion 11 of the nipple 1, and a sealing member 31 in the form of an O-ring seals the gap between the insert 3 and the wall of the large-diameter bore portion 11.

The insert 3 itself has a through hole 30 which, when the insert is mounted, is aligned with the small-diameter bore section 10 of the nipple 1 and opens into it. In its area remote from the nipple 1, the insert 3 has circumferential ribs 32 on its outside to facilitate the holding of a pipe or hose H and an additional O-ring 33 to seal the gap between the insert 3 and an inserted pipe or hose H.

The clamping sleeve 4 has an outer peripheral surface 40 which tapers conically at one end and is intended to contact the inclined inner surface 21 of the plug element 2, and whose diameter must be able to expand and contract as the clamping sleeve moves axially within the plug element 2. The inner diameter of this clamping sleeve 4 should be smaller than the normal outer diameter of any pipe or hose H to be held and is provided with a series of circumferential grooves and ribs to prevent removal of a pipe or hose H once held. In order to enable the clamping sleeve 4 to expand and contract within the plug element 2 as it moves axially, it can be provided with some axially extending slots. However, the clamping sleeve is not limited to this shape.

In order to assemble the pipe coupling of the type mentioned above, first the end of the insert 3 carrying the sealing part 31 is inserted into the large diameter The insert 3 is inserted into the bore section 11 of the nipple 1 until its end rests against the opening of the bore section 10 having a smaller diameter. The clamping sleeve 4 is then placed around the free end of the insert 3 so that its end rests against the opening of the bore section 11 of the nipple 1 having a large diameter. The plug element is then fastened in the circumferential groove 12 of the nipple 1.

In order to connect a pipe or hose H to such a pipe coupling, the pipe or hose H is inserted through the opening 20 of the plug element 2 and between the outer peripheral surface of the insert 3 and the inner peripheral surface of the clamping sleeve 4 until the end of the pipe or hose H touches the end of the opening with the large diameter bore section 11 of the nipple 1.

When the pipe or hose H is under internal pressure, as shown in Fig. 1b, the insert 3 in the large-diameter bore portion 11 of the nipple 1 moves toward the opening 20 of the plug element 2. At the same time, since the pipe or hose H also moves toward the opening 20 of the plug element 2, together with the clamping sleeve 4, the outer peripheral surface 40 of the clamping sleeve 4 comes into contact with the inclined surface 21 of the plug element and is forced to reduce its diameter. In this way, the end portion of the pipe or hose H is firmly held between the inner peripheral surface of the clamping sleeve 4 and the outer peripheral surface of the insert 3.

Although in the illustrated embodiments the main body of the pipe coupling is shown in the form of a nipple 1, the invention is not limited to this form, and the main body may have a different shape.

In the embodiment according to Fig. 1, the plug element 2 is secured to the nipple 1 by caulking. However, this does not have to be the case. The connection can also be made in another suitable way, for example by screwing.

In the embodiment described above, the shoulder between the small diameter bore portion and the large diameter bore portion 11 is used to prevent the insert 3 from being pushed too far into the nipple. However, other arrangements are also possible within the scope of the invention in other embodiments. For example, a nipple having a through hole of uniform diameter can be provided with a C-shaped ring or can be provided with an internal projection between its ends in its central region. In such arrangements, with respect to the point at which the insert 3 is prevented from moving further, the inner circumference on the side of the nipple 1 having the insert 3 is considered to be the large diameter portion 11, while from the point where the insert 3 rests, the small diameter bore portion 10 is to be assumed.

Another special embodiment of the pipe coupling designed according to the invention, as shown in Figs. 3 to 7, is very similar to the embodiment shown in Fig. 1, even if different reference numbers are used there.

The pipe coupling has a cylindrical main body 101 open at both ends, a movable cylindrical insert 102, a cylindrical clamping sleeve 103 arranged between the main body 101 and the insert 102 so that it can move freely back and forth.

The main body is formed by caulking a plug element 101b with one end of a nipple 101a, the tip of the plug element 101b forming a pipe insertion opening 110.

The nipple 101a is provided with a through hole 118 with a large diameter portion 113 and a small diameter portion 114. An inner projection 115 inclined towards the pipe insertion opening 110 is formed at the end of the large diameter bore portion 113 leading into the plug element 101b. The plug element 101b is cylindrically shaped with a certain thickness and then, as can be seen from Fig. 3, has an inclined inner surface 111 adjacent to the pipe insertion opening 110, which is created by reducing the diameter of the plug element 101b towards the opening.

The insert 102 has a large diameter portion 120, a medium diameter portion 121 and a small diameter portion 122 sequentially as shown in Fig. 3, and the large diameter portion 102 is inserted into the large diameter bore portion 113 of the nipple 101a.

The large diameter portion 120 of the insert 102 has a slightly smaller diameter than the large diameter bore portion 113 of the nipple 101a and is provided on its outer surface with a circumferential groove 125 into which an O-ring is inserted to create an airtight seal between the portion 120 of the insert 102 and the bore portion 113 of the nipple 101a.

The middle diameter portion 121 of the insert 102 has an outer diameter that is slightly smaller than the inner diameter of the inner projection 115, as shown in Figs. 3 and 4, and it is provided approximately in the middle of its length with a groove 106 for receiving a C-shaped snap ring 107 which has a circular cross-section and the shape of which can be seen in Fig. 5.

The outer diameter of the C-shaped snap ring is slightly smaller than the inner diameter of the bore portion 113 of the nipple 101a and slightly larger than the inner diameter of the inner projection 115 shown in Fig. 4a.

The small diameter section 122 of the insert 102 has approximately the same diameter as the outside diameter of the pipe to be held and is provided on its outside with a circumferential groove 126 as shown in Fig. 3. An O-ring is arranged in the groove 126 so that when a pipe H is held between the insert 102 and the clamping sleeve 103, an airtight seal is created between the inside of the pipe H and the outside surface of the insert 102 (see Fig. 7).

The insert 102 can slide back and forth between the shoulder existing between the large diameter bore portion 113 and the small diameter bore portion 114 and the inner projection 115.

The clamping sleeve 103 is made of a resilient plastic material and its outer diameter is slightly larger than the diameter of the pipe insertion opening 110. Its outer side has a section 132 tapering towards the pipe insertion opening 110, which corresponds to the inclined inner surface 111 of the plug element 101b, while its inner surface is provided with several ribs 133. In addition, the wall of the clamping sleeve 103 is provided with slots 130, 134 which are alternately open towards one or the other end of the sleeve, as shown in Fig. 6.

When this pipe coupling is assembled as shown in Fig. 3, the gap between the insert 102 and the collet 103 should be slightly smaller than the thickness of a pipe to be inserted therein. Then, when the pipe H is forcibly inserted therebetween, a holding force acts on the pipe H due to the spring-back force of the collet 103. When the pipe H is pulled back in this state, it is held back by the ribs 133 of the collet 103 and by the outer surface of the insert 102. As shown in Fig. 7, the ribs 133 dig into the outer surface of the pipe.

In this embodiment, after connection and when pulling on the pipe H, when the insert 102 slides towards the pipe insertion opening 110, the C-shaped snap ring 107 arranged in the groove 106 of the insert 102 is compressed, reducing its diameter, when it encounters the inner projection 115, as shown in Figs. 4a - 4c. However, once it has passed the projection 115, it returns to its unstressed state. Once a pipe is held, the insert 102 should be displaced against the pipe entry opening 110 to such an extent that the groove 106 passes behind the end of the nipple 101a in the direction of the pipe entry opening 110, so that the C-shaped snap ring 107 assumes its unstressed state in a position closer to the pipe entry opening 110 than the inner projection 115. Once this has occurred, the insert 102 is prevented from displacing backwards even if a pushing force is applied to the held pipe H, because the C-shaped snap ring 107, still partially immersed in the groove 106, can no longer pass backwards past the projection 115. In this way, the connection between the pipe H and the body 101 is stabilized.

The threaded portion at the opposite end of the nipple 101a, remote from the pipe insertion opening 110, may be replaced by other connecting means in other embodiments.

As mentioned in connection with the above-described embodiments, the nipple 101a need not have a through-bore divided into a large-diameter portion 113 and a small-diameter portion 114, and any suitable projections may be provided at approximately the center of a through-bore to limit the inward movement of the insert 102.

Claims (10)

1. Pipe coupling, consisting of: a cylindrical body (1, 2; 101) open at both ends, which is formed from two parts, a first part (1, 101a) which forms a connecting section (13) at one end of the body, and a second part which has the shape of a plug element (2; 101b) at its end remote from the connecting section of the first part and forms a pipe insertion opening (20; 110) at the other end of the body, the second part also having a conical inner surface (21; 111) which tapers in diameter in the direction of the pipe insertion opening (20; 110); a cylindrical insert (3; 102) slidably supported within the body (1, 2; 101), and a clamping sleeve (4; 103) disposed between the inner surface (21; 111) of tapered diameter and the insert (3; 102) in such a way that it is freely slidable back and forth, leaving a gap between the clamping sleeve (4; 103) and the insert (3; 102) for receiving and holding the end edge of a pipe (H) inserted into the opening (20; 110), characterized in that the insert (3; 102) is slidable over a predetermined range in the first part (1, 101a) which has an inwardly directed projection (15; 115) at its insertion opening (20; 110) opposite end to prevent the insert (3; 102) from escaping from this opening. 2. Pipe coupling according to claim 1, wherein the inwardly directed projection (15; 115) is inclined towards the pipe insertion opening (20; 110). 3. Pipe coupling according to claim 1 or 2, wherein the first part (1, 101a) of the body has a through hole with a small diameter portion (10; 114) and a large diameter portion (11; 113), and wherein the projection (15; 115) is arranged at the end of the large diameter portion facing the pipe insertion opening (20, 110). 4. Pipe coupling according to claim 3, in which the first part (1, 101a) of the body has a circumferential groove (12) on its outer side, onto which the plug element (2; 101b) is applied, and the displaceable insert (3; 102) is retained in the large diameter section (11; 113) by a sealing ring (31) arranged there, the insert having a through bore which is aligned with the small diameter bore section (10; 114) of the first part. 5. Pipe coupling according to claim 3 or 4, in which a C-shaped snap ring is arranged in a groove (106) in the outer surface of the insert (102), the outer diameter of the snap ring (107) in the uncompressed state being larger than the large diameter bore portion (113) of the first part (101a), whereby the insert (102) is prevented from sliding back into the first part once it has been moved sufficiently far towards the pipe insertion opening (110) to release the snap ring (107) from the bore (113). 6. Pipe coupling according to claim 5, wherein the outer diameter of the C-shaped snap ring (107) in its non-compressed state is larger than the inner diameter of the inner projection (15). 7. Pipe coupling according to claim 5 or 6, wherein the C-shaped snap ring (107) has a circular cross-section. 8. Pipe coupling according to one of the preceding claims, in which the clamping sleeve (4; 103) has an outer peripheral surface which can come into contact with the inclined inner surface (21; 111) of the plug element (2; 101b) and is shaped so that its diameter can increase or decrease while it slides in the axial direction in the plug element. 9. Pipe coupling according to one of the preceding claims, in which the outer diameter of the clamping sleeve (4; 103) is slightly larger than that of the pipe insertion opening (20; 110) and the clamping sleeve is provided with at least one longitudinal slot (42; 130). 10. Pipe coupling according to one of the preceding claims, in which the plug element (2; 101b) is removable from the first part (1; 101a) of the body.